deps: bump getlantern/amp to include the closed-channel crash fix (amp#18)

Bumps github.com/getlantern/amp 20260305 (782bc8045e58) -> 20260606
(a8629924577c) to pull in amp#18, which removes the close(chDB) that races
the keepcurrent Runner and crashes the client with "send on closed channel"
(Freshdesk #176970). Build/vet pass; go mod tidy run, go.mod + go.sum together.

First hop of propagating the fix to clients; radiance and lantern bumps follow.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: myleshorton

go.mod

@@ -5,7 +5,7 @@ go 1.25.0
 require (
 	github.com/Jigsaw-Code/outline-sdk v0.0.19
 	github.com/Jigsaw-Code/outline-sdk/x v0.0.2
-	github.com/getlantern/amp v0.0.0-20260305201851-782bc8045e58
+	github.com/getlantern/amp v0.0.0-20260606002220-a8629924577c
 	github.com/getlantern/dnstt v0.0.0-20260603191204-3b860502c0ac
 	github.com/getlantern/domainfront v0.0.0-20260419161617-0bff0b2169f4
 	github.com/stretchr/testify v1.11.1

go.sum

@@ -51,8 +51,8 @@ github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1m
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/flynn/noise v1.0.1-0.20220214164934-d803f5c4b0f4 h1:6pcIWmKkQZdpPjs/pD9OLt0NwftBozNE0Nm5zMCG2C4=
 github.com/flynn/noise v1.0.1-0.20220214164934-d803f5c4b0f4/go.mod h1:xbMo+0i6+IGbYdJhF31t2eR1BIU0CYc12+BNAKwUTag=
-github.com/getlantern/amp v0.0.0-20260305201851-782bc8045e58 h1:3wxMKw90adxiEzsJmAmMHqBJQr/P/9Goqy/U2a1l/sg=
-github.com/getlantern/amp v0.0.0-20260305201851-782bc8045e58/go.mod h1:p6WdG48YAz5SCUpiMSGLy616A6YghKToc63y3NP7avI=
+github.com/getlantern/amp v0.0.0-20260606002220-a8629924577c h1:ZzxuhIWO295y4eE6wPYUq8Smntlgg+y39L5OOyMJY+k=
+github.com/getlantern/amp v0.0.0-20260606002220-a8629924577c/go.mod h1:b5teAOFT+vpBqc2CHoz74QTEM15iOv1PLdQogwXcfrM=
 github.com/getlantern/dnstt v0.0.0-20260603191204-3b860502c0ac h1:TMvkNgLVyIYAfu1dYrOuRPYMVY+cHEo1C0CYWhtSw2A=
 github.com/getlantern/dnstt v0.0.0-20260603191204-3b860502c0ac/go.mod h1:0+wlia2hljruM7rhjzBMFhve011lGRO0OxjVSOcXBoQ=
 github.com/getlantern/domainfront v0.0.0-20260419161617-0bff0b2169f4 h1:/Q9FJvKPyuXfH6tfA+C+t9/AbvGWs3Yp9iqI74FYvb4=